Accordingly, the computer has already penetrated into each family and enterprise to become an indispensable electronic product in our modem daily lives. Following the prevalence of computer multimedia, more accessory products are needed for input and output, wherein the scanner is one important item of them for processing image or inputting character data, so the usage range of the scanner is very extensive.
Currently, the optical scanner that is applied for ordinary document uses a light source arranged on the lamp seat to irradiate light onto the document and picture, from which the reflected light is again reflected through several reflection mirrors and finally enters into the photoelectric coupling element to be converted into electronic signals that are processed by the circuit to display as a scanned image. Therefore, the stability, the uniformity and the intensity of the light generated from the light source will influence the quality of the scanned image, because the reflected light of the poor or insufficient light source will make the image generated from the photoelectric coupling element be unrealistic or generate unnecessary noise to influence the normal scanning quality of the scanner.
Please refer to FIG. 1, which is a 3-D structure for illustrating a flatbed-type optical scanner typically seen in the current market. Mainly, a manuscript supporting glass 12 is arranged at the top surface of the outer shell 11 of an optical scanner 1 for supporting a reflective manuscript 15. Through being driven along by a driving device 13, an image picking-up device 2 makes a linear motion along a guiding rod 14 in the hollow outer shell 11, such that an image scanning job is executed on the reflective document 15 supported upon the manuscript supporting glass 12.
Please refer to FIG. 2, which illustrates a light-source module in the image picking-up device according to the prior art. As shown in FIG. 2, a light-source module 20 is designed in an image picking-up device 2 of FIG. 1. A rectangular lampholder 201 in the light-source module 20 provides a (mechanical) support to light source (e.g., lamp tube 200). A reflection piece 202 is arranged at the inside surface of the lampholder 201 for focusing and compensating the light emitted from the lamp tube 200 and then reflecting it onto the manuscript 15. However, since the brightness of the light source is restricted by the fluorescent tube itself, so the uneven brightness will influence the quality of the scanned image.
When an optical scanner executes a scanning job upon an object to be scanned, for example, the light-source module 20 irradiating light onto the manuscript 15 as shown in FIG. 2, the light will pass through an opening 210 and be projected toward the manuscript 15 and, except the light irradiated from the lamp tube 200 and directly projected toward the manuscript 15, there is also another light coming from the light source but reflected from the reflection piece 202 in the lampholder 201 to be projected upon the manuscript 15, so all the reflected light and the irradiated light will be projected upon the scanning range 150 of the manuscript 15. However, the shortcoming of this arrangement is that the light 22 reflected from the reflection piece 202 will be incident upon the second scanning ranges 151, 152 of the manuscript 15 because of the reflection angle, and the light 22 incident upon the second scanning range 151 is wasted and insufficiently used. Because only one unit scanning line is scanned in every unit time during the scanning process of a scanner, for example, the first scanning range 150, the light 22 incident outside the first scanning range 150 (for example, the second scanning ranges 151, 152) is not utilized completely, and this is very inefficient. If the light 22 incident upon the second scanning ranges 151, 152 may be changed to be incident upon the first scanning range 150, then it means that the light source may be utilized in a more efficient way, because the manuscript 15 will be projected with more intensive light and a superior quality of scanned image may thereby be obtained.